/
propagation.py
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/
propagation.py
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"""File demonstrating the use of propagators (examples)
"""
import numpy as np
from beyond.beyond.dates import Date, timedelta
from beyond.beyond.orbits import Orbit
from orbidet.propagators import ImportedProp, Cowell, Semianalytical
from orbidet.force import Force,TwoBody,AtmosphericDrag,GravityAcceleration,ExponentialDragDb
from orbidet.satellite import SatelliteSpecs
from orbidet.metrics.plot_utils import *
forms = {'cartesian':['x','y','z','vx','vy','vz'],
'keplerian':["a", "e", "i", "RAAN", "w", "TA"],
'keplerian_mean':["a", "e", "i", "RAAN", "w", "M"],
"equinoctial_mean":["a","h","k","p","q","lmb"]
}
def ImportedPropExample():
# defining initial conditions and setting propagator
start = Date(2010,3,1,18,00,0)
filename = "./orbidet/data/trajectories/GMAT1.csv"
prop = ImportedProp(start, filename=filename)
initialState = prop.orbit
# print(repr(initialState))
# getting generator
step = timedelta(seconds = 5)
stop = start + timedelta(hours = 1)
gen = prop.iter(step=step,stop=stop,start=start)
# generate orbit
for orbit in gen:
print(orbit.date, orbit)
def CowellExample():
# defining initial conditions & frames
start = Date(2010,3,1,18,00,0)
step = timedelta(seconds = 5)
stop = start + timedelta(hours = 1)
integrationFrame = "TOD"
gravityFrame = "PEF"
initialOrbit = Orbit(np.array([6542.76,2381.36,-0.000102,0.3928,-1.0793,7.592]),
start,"cartesian",integrationFrame,None)
# creating satellite
sat = SatelliteSpecs("SAT1", #name
2, #CD
50, #mass [kg]
2) #area [m²]
# creating force model
force = Force(integrationFrame = integrationFrame, gravityFrame = gravityFrame)
grav = GravityAcceleration(5,5)
DragHandler = ExponentialDragDb()
drag = AtmosphericDrag(sat,DragHandler)
two_body = TwoBody()
force.addForce(grav)
force.addForce(drag)
force.addForce(two_body)
# print(force)
# creating propagator & generator
prop = Cowell(step,force,method="RK45",frame=initialOrbit.frame)
initialOrbit.propagator = prop
gen = initialOrbit.iter(stop=stop,step=step)
# generate orbit
for orbit in gen:
print(orbit.date,orbit)
def SemianalyticalExample():
# defining initial conditions & frames
start = Date(2010,3,1,18,00,0)
output_step = timedelta(seconds = 60)
propagation_step = timedelta(hours = 1)
stop = start + timedelta(hours = 5)
integrationFrame = "TOD"
gravityFrame = "PEF"
initialOrbit = Orbit(np.array([6542.76,2381.36,-0.000102,0.3928,-1.0793,7.592]),
start,"cartesian",integrationFrame,None)
# creating satellite
sat = SatelliteSpecs("SAT1", #name
2, #CD
50, #mass [kg]
2) #area [m²]
# creating force model
force = Force(integrationFrame = integrationFrame, gravityFrame = gravityFrame)
grav = GravityAcceleration(5,5)
DragHandler = ExponentialDragDb()
drag = AtmosphericDrag(sat,DragHandler)
two_body = TwoBody()
force.addForce(grav)
# force.addForce(drag)
force.addForce(two_body)
# print(force)
# creating propagator & generator
prop = Semianalytical(propagation_step,force,method="RK45",frame=initialOrbit.frame,
quadrature_order = 20, DFT_lmb_len = 32, DFT_sideral_len=32,
outputs=("mean","osculating"))
initialOrbit.propagator = prop
initialOrbit.state = "mean"
gen = initialOrbit.iter(stop=stop,step=output_step)
ephm_osc = []
ephm_mean = []
output_form = "equinoctial_mean"
# generate orbit
for mean,osc in gen:
ephm_osc.append(osc.copy(form=output_form))
ephm_mean.append(mean.copy(form=output_form))
print(mean.date)
# Time array
dt = (ephm_osc[1].date - ephm_osc[0].date).total_seconds()
delta_t = (ephm_osc[-1].date - ephm_osc[0].date).total_seconds()
t = [t_i for t_i in range(0,round(delta_t+dt),round(dt))]
xlabel = 'Time [s]'
for ephm,label in zip([ephm_osc,ephm_mean],["osc","mean"]):
x0 = [x[0] for x in ephm]
x1 = [x[1] for x in ephm]
x2 = [x[2] for x in ephm]
x3 = [x[3] for x in ephm]
x4 = [x[4] for x in ephm]
x5 = [x[5] for x in ephm]
plot_graphs(x0,t,forms[output_form][0],"",xlabel,i=0,label=label,show_label=True)
plot_graphs(x1,t,forms[output_form][1],"",xlabel,i=1,label=label,show_label=True)
plot_graphs(x2,t,forms[output_form][2],"",xlabel,i=2,label=label,show_label=True)
plot_graphs(x3,t,forms[output_form][3],"",xlabel,i=3,label=label,show_label=True)
plot_graphs(x4,t,forms[output_form][4],"",xlabel,i=4,label=label,show_label=True)
plot_graphs(x5,t,forms[output_form][5],"",xlabel,i=5,label=label,show_label=True)
show_plots(True)
def main():
SemianalyticalExample()
if __name__ == "__main__":
main()